Grinding-machine.



J. W. ,BOYNTON. GRINDING MACHINE.

APPLICATION FILED JULY 28, 1910. Patented Feb. 11, 1913.

2 snnms-snnn'w 2 '5; TED STATES PATENT OFFICE.

JOHE' W. BOYNTON, OF ATHOL, MASSACHUSETTS, ASSIGNOR TO UNION TWIST DRILLCOMPANY, OF ATHOL, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

GRINDING-MACHINE.

Specification of Letters Patent. Application filed July 28, 1910. SerialNo. 574,366.

To all whom it may concern Be it known that I, JOHN W. BOYNTON,

a citizen of the United States, residing at sharpener for millingmachine cutters. In sharpening these cutters. it is a matter of greatdifficulty to effect a grinding of the radial cutting face of the toolwhich will leave the points of the teeth equidistant from the axis ofrotation. This feature of the sharpening, which is of the greatestimportance, is complicated on. account of the rearward clearance of thecutter teeth. It is, of course, obvious that in a succession of cutterteeth which are calculated to take ofl a chip of say two one thousandthpart of an inch in thickness, any variation in the length of the pointsof the teeth will render ineffective those teeth'which are shorter thanthe maximum, thus retarding the speed at which the work may be done.

It is the object of m present invention to provide for the grin ing ofcutter teethso as to produce absolute uniformity in the length of thepoints of the teeth and otherwise to secure, identity of treatment inthe successive teeth of the cutters being ground. I accomplish thisessential feature by introducing a stop in the path of the abrading diskwhich shall be effective, not only to protect the teeth of the cutteragainst an excessive grinding, but, which would also co-act with thedisk itself to keep it true at all times. i The construction andoperation of my device will be more fully described in the specificationwhich follows and in the drawings which form a part of the specificationI have shown as an illustrative embodiment of my invention a machineincluding in its structure a forni'of my invention which I have foundwell adapted to practical use.

Throughout specification and drawing like reference numerals areemployed to in-. dicate corresponding parts and in the drawings:Figure 1is a side view of my machine, Fig. 2 is a partial front View partlyhorizontal section, Fig. 4 is a fragmentary view of a portion of thegrinding wheel at work on a tooth, and Fig. 5 is a similar viewillustrating the effect of the interposed stop.

Upon a suitable base 1 of my grinding machine is formed a lateralbracket 2 which carries a bed 3 upon which a slide 4 is longitudinallymovable by a screw 5 controlled by a milled knob 55. 6 is a cross slidecontrolled by a second milled knob 7 and upon this cross slide aresuitable bearings 8, within which is journaled a spindle 9 turned by apulley 9 On the end of the spindle 9 is an emery wheel 10 protected by a.hood 11. 13 is a second bracket supporting a work slide 12 which ismoved by a rack 12 engaged by a pinion 13 which is controlled by a knob14.

15 is a plate adjustably held on' the slide 12 by a set screw 16 whichpasses through a slot in the plate.

17 is a screw stud for holding a cutter X.

On the forward end of the slide 12 is adjustably mounted a'stud 18.which has a carbon or so called diamond point 18 in its end. This ointconstitutes a stop and truing point or the abrasive wheel 10. Thefunction and operationof this stop may perhaps best be understood by adescription of the operation of my device in grinding the teeth m of thecutter X. The operation is as follows :-First, adjust the diamond truingpoint 18 to the central plane of the stud 17 and true ofl the front faceof the emery wheel by advancing the wheel by means of the knob 5 and bymoving the slide 15 back and forth by turning the knob 14. Supposingthat the proper plate 15 has been selected which has the screw stud 17of the desired size for the cutter which is to be sharpened, the cutteris then clamped in place, as indicated in Figs. 2 and 3.

In setting the cutter, the tooth m, which is to be sharpened, is rotatedast the true plane which passes through t e point 18 and the center ofthe stud 17 by a distance of from one to two thousandths of an inch,

Patented Feb. 11,1913.

gradually the tooth a: of the cutter X is successively brought past theworking face of the wheel 10 which is gradually advanced by turning" theknob 5. The relative position of the tooth and the emery disk duringsuch an advance of the cutter is illustrated in Fig. 4 in which theworking face of the excess of turn on the knob 5 at the last traverse ofthe slide 15 would carry the face of the wheel beyond the plane to becut. It is to be noted, however, that the stop and truing point 18 hasbeen set in the exact plane of the ultimate face which is sought andwhich is to be reached by the grinding. Supposing, therefore, that thewheel be advanced a little too far. As theslide comes forward the truingpoint and stop 18 begins to travel across the working face of the disk10, as indicated in Fig. 5. In this figure, 10 indicates the originalworkin face and 10 indicates the trued ofi' WOI'klIlg face which hasbeen passed over by the point 18 It will be seen, therefore, that theface 10 is now' exactly in the plane of the face which is sought. I haveindicated the ultimate face thus sought by dotted lines on this tooth inthis figure. It will thus be .seen that it is possible for the workmanto grind the tooth' with great rapidity and as a matter of actualpractice the'grinding wheel 10 on the last cut is brought up until theworkman hears the easily distinguishable sound of the diamond point 18incontact with the S111"!- face 10 of the wheel 10. This, of course,

wears away the wheel, but, the wear is so slight that'it is fullycompensated for'by the fact that the surface is trued and kept trued foreach tooth.

The great advantages of this simple combination of elements will bereadily understood. by those skilled in the art. It makes of the truingpoint a protective stop beyond which the face of the cutting wheel maynot be advanced by the very fact that the point 18 removes the facebefore .it comes in contact with the tooth of the cutter. This, ofcourse, assures a perfection of grinding in the cutters and makespossible a uniformity in the tooth length.

Various modifications in the arrangement of the point and in theconstruction of the various parts of the machine may obviously be made,all without departing from the spirit of my invention if within thelimits of the appended claim.

What I, therefore, claim and desire to secure by Letters Patent is In amachine for inding milling machine cutters, an abra ing wheel, means forsupporting said wheel, said means being longitudinally and laterallymovable, a supportin slide for a toothed cutter laterally movab e withrespect to said abrading wheel, means for moving said slide and a stoponsaid slide oppositely disposed to be effective in the long1tudinalmovement of said abradin wheel and adjustable to the true plane 0 thedesired face of the cutter tooth to be ground.

f In testimony whereof I aflix my signature in resence of" twowitnesses.

